Design of engineered surface for performance improvements of hydraulic pumps

Abstract

The main target of this research activity is the development of techniques for increasing the performance of external gear pumps. Gear pumps are fixed displacement machines widely used in fluid power systems since they have low cost and high reliability. Some components are very critical to be designed, such as the lateral plates, on whose characteristics the efficiency of the entire pump depends. This research activity focuses on increasing the hydrodynamic bearing capacity in the meatus between gear wheels and lateral plates by means of engineered surfaces, in order to reduce the wear of the components and increase the useful life of the machine. The analysis of the fluid meatus was carried out by means of CFD analysis. Numerical simulations made it possible to evaluate the effect that the creation of a textured surface on the lateral plates has in increasing the hydrodynamic bearing capacity of the lubricated coupling. Great attention has been paid to the study of cavitation phenomenon, with the implementation of a cavitation model within the CFD code that allows to simulate both gaseous and vaporous cavitation. The model was validated through experimental activity on the flow through an orifice placed in a hydraulic circuit. Numerical simulations made it possible to identify the best geometric characteristics on which to concentrate a wide experimental activity. The samples of the lateral plates have been made by laser marking and the geometric characteristics were verified by means of an optical profilometer. Subsequently, bench tests have been conducted to obtain the efficiency values of pumps with textured lateral plates, to be compared with those of standard pumps. The experimental activity required the definition of a running-in cycle and a specific test cycle; special components made particularly for this research activity have been also used, in order to obtain reliable results, but with test times compatible with those of the university laboratory, also considering the high number of samples tested. The results obtained are very promising showing that pumps with textured components inside perform better than the standard and create the basis for future developments.